1) He has never fired that rifle with those sights before. We know this because if he had, he would have fixed the impossible-to-use setup that he has there.

2) Even though he's never used those sights with that gun before, he's trusting his life and the lives of those around him to its accuracy -- and to his ability to use that setup accurately under stress. We know this because he's using it during an actual encounter where lives are at stake.

3) Neither his immediate supervisor nor any of his squad mates know how to use that type of sight, either. We know this because if they did, they would have corrected his error.

Actually, we don't "know" any of that. It is all inferred. It may be that he has fired his rifle with the iron sights, got the Eotech, popped it on and got a call out. You can see through the Eotech backwards and so he can see his iron sights. Since his supervisors know he can still use his iron sights, nobody has seen fit to have to remove the Eotech during the immediate crisis.

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"If you look through your scope and see your shoe, aim higher."
-- said to me by my 11 year old daughter before going out for hogs 8/13/2011